Each subject taking part at the study received a 75-g 2-h Oral Glucose Tolerance Test (OGTT) at 16-18 and/or 24-28 weeks. The diagnosis of gestational diabetes mellitus was made for any glucose value exceeding the normal cut-off, as reported by the Guidelines. If OGTT is pathological, women are referred to other health care specialists for further clinical evaluation and/or specific treatment.